There might not be a more difficult profession than the creation of magical items. A competent enchanter could spend months or years crafting a single item, painstakingly ensuring every single detail was perfect.

The Rune Knight has no such time for that. They have studied the glyphs and runes used by enchanters, and created an 'abridged' version of it. A wizard would look at their work and call it 'nearly incomprehensible nonsense', but the Rune Knight can use the faint glimmer of arcane talent in them to draw power from their Runic Inscriptions, and combine it with their martial prowess to create a weapon of immense potential power- The Rune Blade. By studying each of the eight schools of magic, the Rune Knight has condensed the essence of each school into a powerful Rune.

Made with great cost and care, the Rune Knight is little more than an average warrior without their chosen instrument in hand. However, if you ever see a fighter that wields a blade lined with glowing runes, flight might be your best option.

Rune Blade

At 3rd level, you have learned how to transform any melee weapon into a Rune Blade. By spending 4 uninterrupted hours, you can inscribe a weapon with magical runes and gems that allow you to channel certain energy through contact. This requires you to use Jeweler's Tools as well as an amount of gems and powdered silver equal to 4 x the weapon's value, which are consumed in the process. Once a weapon has been transformed into a Rune Blade, it cannot be undone.

In addition, because they are imperfect enchantments, only a Rune Knight can activate the Runic Inscriptions. When any creature who isn't a Rune Knight attempts to wield a Rune Blade, the Runic Inscriptions become inert.

When you create a Rune Blade, it is only with the Runic Inscriptions you know at the time. If you gain new Runic Inscriptions after creating a Rune Blade, you must repeat the transformation process on that weapon to be able to use the new Inscriptions.

Weapons that are already enchanted can also be transformed into a Rune Blade without disrupting the previous enchantment, however, the GM may impose an Arcana skill check if the selected weapon has a particularly powerful or ancient enchantment. On a failed check, the previous enchantment is permanently lost.

The Rune Blade always requires attunement, even if the original weapon did not. If the original weapon previously required attunement, then it will instead use two attunement slots after it has become a Rune Blade. If an existing enchanment is lost during the process of creating a Rune Blade, any previous requirements of attunement are also removed from the weapon.

In addition, you also gain proficiency with Jeweler's Tools and Arcana.

Edge of Arcana

At 3rd level, you have learned how to inscribe a set of runes that channel the eight schools of magic through your blade, and activate them in the heat of battle.

Choose three of the Runic Inscriptions below. These will comprise the totality of your enchantment. You gain knowledge of additional Runic Inscriptions at 6th, 8th, 10th, 14th and 18th levels.

As a bonus action, you may activate one of the Runic Inscriptions on the Rune Blade you wield to receive the associated enchantment. The activated Runic Inscription glows along the Rune Blade, giving off 5 feet of bright light, and a further 5 feet of dim light whilst activated, and if there was already an active Runic Inscription, it is replaced with the newly selected enchantment. 

In addition, attacks with your Rune Blade while a Runic Inscription is active are considered magical for the purposes of damage resistance against non-magical attacks.

Edge of Arcana Options

At 3rd level, you have learned how to inscribe a set of runes that channel certain schools of magic through your blade, and activate them in the heat of battle.

Choose three of the Runic Inscriptions below. These will comprise the totality of your enchantment. You gain knowledge of additional Runic Inscriptions at 6th, 8th, 10th, 14th and 18th levels.

Blessed Blade

Channelling the power of the school of Divination, the Rune Blade hums with a divine light, and almost seems to move of its own accord. Whenever you make a melee weapon attack with the Rune Blade, roll 1d4 and add the result to your attack roll and you do not suffer the effects of disadvantage against your target, nor do they benefit from cover. This ability cannot cancel disadvantage to give you advantage.

Brilliant Blade

Channelling the power of the school of Illusion, light reflects strangely off your Rune Blade while this enchantment is active, refracting into a spectrum of colours at different angles.  After one of your attacks during the attack action, you can attempt to blind all creatures within 5 feet of you, creatures targeted must make a Wisdom saving throw. If they fail, roll 4d10 + twice your Fighter level. If any of the creature's current hit point total is less than the total amount, then the creature becomes blinded until the end of your next turn.

The difficulty class for the saving throw is 8 + your proficiency bonus + your Intelligence modifier.

Chromatic Carve

Channelling the power of the school of Evocation, the glowing runes across your weapon hum brightly, changing colour with each pulse. Whenever you use the Attack action, select a damage type: acid, cold, fire, lightning, poison, or thunder. Until the end of your turn, add 1d6 of the selected damage type to each successful weapon attack with your Rune Blade.

At 11th level, the damage die for this ability becomes 1d8. At 17th level, it becomes 1d10.

Coiling Chains

Channelling the power of the school of Conjuration, a thin, pitch-black chain churns and wraps around your weapon while this enchantment is active. Whenever you take the attack action, you may forego 1 attack to instead attempt to bind an enemy with the chain. Choose a creature within 5 ft. of you. That creature must make a Strength saving throw or become Restrained until the start of your next turn. You cannot use this ability if a creature is already restrained by this effect. The creature may use an action to repeat the saving throw during their turn. If they succeed, the effect ends.

The difficulty class of the saving throw is 8 + your proficiency bonus + your Intelligence modifier. 

Displacer Drive

Channelling the power of the school of Enchantment, time itself seems to bend around your Rune Blade when this enchantment is active, temporarily slowing those that are struck by it. Creatures that take damage from your Rune Blade lose -1 AC and cannot take reactions until the beginning of their next turn. A creature cannot be affected by this ability more than once at a time.

Additionally, once per long rest, as a reaction, the creature attacking you must make a Wisdom saving throw, on a failed save the target disappears and reappears in the space it ended its previous turn or in the nearest unoccupied space if that space is occupied.

The difficulty class for the saving throw is 8 + your proficiency bonus + your intelligence modifier.

Ever-Changing Blade

Channelling the power of the school of Transmutation, your Rune blade shifts and moulds itself into any form that you wish. When activating this enchantment, you may change your Rune Blade into any other type of weapon or object. In this new form, the Rune Blade keeps it's original properties, such as the Finesse or Light properties, as well as any magical effects it may have had, whilst gaining the properties of the object or weapon it has become including damage die and type.

If the Blade takes the form of a ranged weapon, any necessary ammunition is created in the form of magic from the runes inscribed on the blade.

The Rune Blade retains this form until the enchantment is deactivated, or is replaced by another Runic Inscription.

Reaping Rake

Channelling the power of the school of Necromancy, foul energies and an unnatural coldness seep from your weapon while this enchantment is active. Whenever you make a successful weapon attack, gain hit points equal to half of the total physical weapon damage dealt (rounded down).

Shimmering Swipe

Channelling the power of the school of Abjuration, with every swing of your weapon, faint barriers are woven behind it. Each time you make a melee weapon attack with your Rune Blade that hits, gain +1 AC until the beginning of your next turn.

Once per short rest, as a reaction, you can empower the barriers against a single attack, doubling the effect gained for this attack, but fading immediately after the attack.

Spell Sunder

At 7th level, you gain the ability to disrupt hostile magics with your Rune Blade. When you are targeted by a spell cast by a hostile creature, you can use your Reaction to attempt to sunder it. Make an attack roll with your Rune Blade to match or exceed the spell's AC, calculated below. If the attack is successful, you avoid all effects of the spell.

The AC of the triggering spell is 14 + the level of spell slot used to cast the spell.

If you roll a 20 on the die for your Spell Sunder attack roll, then you also capture the spell, gaining 1 charge. Whenever you make an attack roll that hits, you may expend the charge and release the captured spell against the creature being attacked. That creature receives the effects of the spell that was sundered as if they had been targeted by it. Any necessary calculations are made using the statistics of the original caster, and if the spell's duration was concentration, then the duration is 1 round instead.

Charges gained by capturing a sundered spell are lost after 1 minute.

Once you have used this ability, it cannot be used again until you complete a short or long rest.

Overflowing Power

At 10th level, you learn how to intensify the power of your runic enchantments when it counts. 

When you make a melee attack roll using a Rune Blade with one or more active enchantments, you can expend 1 Extra Attack to empower the enchantment(s).

If dice are rolled as part of the enchantment's effects, roll twice as many dice and use twice as many results. If a saving throw is made as part of the enchantment's effects, it is made at disadvantage. If AC is affected as part of the enchantment's effects, double the amount received.

Arcana Mastery

Starting at 15th level, your mastery of Arcana allows you to improve your Rune Blade to activate two enchantments at once, instead of one.

If you attempt to activate a 3rd enchantment while two are already active, you can choose which of the current enchantments to replace.

You also gain expertise in Arcana.

Runic Mastery

Starting at 18th level, you can ignite one rune on your Rune Blade as a bonus action, causing the effect of that rune to be quadrupled for 1 minute.

If dice are rolled as part of the enchantment's effects, roll four times as many dice and use four times as many results. If a saving throw is made as part of the enchantment's effects, it may target two creatures and is taken at disadvantage. If AC is affected as part of the enchantment's effects, quadruple the amount received.

When the effect wears off, the rune is erased from the Rune Blade and must be engraved onto the blade before being usable again.